If the inverter power supply circuit failure, check the route according to the battery terminal voltage → final push-pull drive transistor → battery bank 30A fuse automatic protection circuit → pulse width modulation components → power off switch matrix → output circuit. Among them, to the storage of electricity he end voltage is too low, resulting in failure of the failure rate is higher. Such as a SENDON UPS-1000 uninterruptible power supply, no output on the power on, and there is no hint of alarm information, can not work in the inverter power supply and utility power supply state. According to its working principle, according to the above steps to detect the actual line, and finally found that the battery voltage is too low. Each battery terminal voltage has dropped from 12V to about 6V, which causes the automatic protection circuit to operate, and it is necessary to equalize the charging of this small sealed lead battery. As there is no special high-efficiency safety UPS power constant current charger on hand, so the use of transistor DC regulated power supply and slide line varistor, the battery pack for equalization of charging, the specific method is: WVJ-3A with self-protection transistor DC regulated power supply, the positive output is divided into four strands, respectively, with the four specifications of the positive end of the 12V, 24Ah / 20hR battery connected to the end. The negative output of the DC regulated power supply, through the 200Ω/300W sliding-wire transformer, and then divided into four strands connected to the negative terminal of the four batteries, the batteries are connected in parallel. The beginning of charging the battery internal resistance is found to be large, the voltage to 21V, charging 5h, the voltage to 18V, gradually lower the voltage, while moving the slide wire varistor to adjust the charging current, charging 12h, the battery voltage returns to normal, the installation of the power supply to return to normal power supply. In addition, apc ups power supply final stage push-pull drive transistor is more likely to be damaged, and most of them are open circuit between the base and the emitter, resulting in no output of the inverter or transformer has an abnormal sound and so on
Disassemble the apc ups power supply to carry out a visual inspection. Check whether the cable connection plug is loose, whether there are abnormalities on the surface of various components, such as whether there is a special smell, whether the fuse is blown, and whether there is a broken wire, open weld or poor contact and other phenomena;
such as the utility power supply circuit failure, you can check from the input level backward step by step, but also from backward to forward check. Check the route according to the input AC mains voltage → automatic voltage stabilization control circuit → anti-jamming control circuit → relay switch matrix → conversion control circuit → output circuit;